National Aeronautics and Space Administration National Aeronautics and Space Administration Hypervelocity Impact Testing and MMOD Risk Reduction NASA Hypervelocity Impact Technology (HVIT) Group Eric Christiansen/JSC-XI4 Dana Lear/JSC-XI4 Jim Hyde/JSC-XI4 (JETS) https://ntrs.nasa.gov/search.jsp?R=20190000845 2020-06-22T13:47:27+00:00Z
22
Embed
Hypervelocity Impact Testing and MMOD Risk Reduction€¦ · Impact tests demonstrated methods to toughen thermal blankets against MMOD impacts: – Beta cloth and fiberglass cloth
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
National Aeronautics and Space AdministrationNational Aeronautics and Space Administration
Hypervelocity Impact Testing and MMOD Risk Reduction
• Purpose:– Provide data to develop, update, and/or verify ballistic limit equations
used in the MMOD risk assessment– Provide data used to compare two or more shielding options to
reduce MMOD risk– Determine failure modes and failure criteria for hardware
• Failure modes: how hardware fails (pressure vessels, pressurized lines, electronic hardware, power cables)
• Failure criteria: quantify damage level that results in hardware failure (for example: depth of penetration into pressure vessel that results in leak or burst)
National Aeronautics and Space Administration
3
ISS Lithium-Ion Battery Tests
Test: HITF-12143, 1cm diameter Al @ 6.86 km/s
National Aeronautics and Space Administration
4
ISS Lithium-Ion Battery Tests
Post-test photos from HITF-12143, 1cm diameter Al @ 6.86 km/s
• Energetic response to hypervelocity impact
National Aeronautics and Space Administration
5
ISS Lithium-Ion Battery Tests
Post-test photos of test chamber floor after test HITF-12143, 1cm diameter Al @ 6.86 km/s
• Hundreds of centimeter size metallic fragments ejected from the battery cell
Each of the blocks (white/black checker board) in this ruler are 1cm long
National Aeronautics and Space Administration
6
MMOD Damage to ISS Solar Array Masts
• Elements of the solar array masts have been damaged from MMOD impacts
• If critical damage to mast elements found during inspection, solar array will need to be operated under restricted/protect flight rules
ISS038e006032, Nov. 2013
National Aeronautics and Space Administration
7
National Aeronautics and Space Administration
8
Impact into fused silica glass
• Test HITF-14079: 3.6mm diameter Nylon spherical projectile at 7.16 km/s, 0 deg impact angle; target: 12.7mm thick fused-silica glass
Typical DC Shield(Whipple shield with MLI thermal blankets)
BUMPER Code Finite Element Model
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0 5 10 15
Velocity (km/s)
Criti
cal A
l Pro
j. Di
amet
er (c
m)
dc @ 0dc @ 45dc @ 60data @ 0data @ 45data @ 60
DC-1 Ballistic Limit Equations and HVI Test Data
Shield Failure expected above curvesOpen symbols = no-failure data
Closed symbols = shield failure data
0.1cm Aluminum AMG6 bumper
MLI
1.7cm
0.4cm Aluminum AMG6 pressure shell
MLI
Ballistic Limit of shield (typical):0.35cm Al projectile @ 7km/s, 0o
DC
National Aeronautics and Space Administration
10
MMOD Protection
• Iteration of spacecraft MMOD protection design and operations is key to meeting MMOD requirements with minimum mass– Hypervelocity impact tests needed to verify ballistic limit equations
used in the risk assessment
National Aeronautics and Space Administration
11
Methods to Reduce MMOD Risk• Iterate analysis & test
– focus on risk drivers– Include MLI (in BLEs), include shadowing hardware (in FEM), include
thicker/more robust structures (in FEM)– Perform impact tests on risk drivers, evaluate risk reduction alternatives
• Operations – if possible, assess attitudes to reduce MMOD risk while meeting mission
• Design– Increase standoff (30x desired average projectile diameter want to stop to meet
requirements)– Toughened thermal blankets– Improve rear wall: add or substitute high-strength materials– Adequate bumper thickness (mass per unit area): all bumpers should have 20%
of critical projectile mass per unit area
National Aeronautics and Space Administration
12
Toughened thermal blankets
• Impact tests demonstrated methods to toughen thermal blankets against MMOD impacts:– Beta cloth and fiberglass cloth for disrupter layer– Open cell polyimide foam for spacer layer– Spectra 1000-952 for stopper layer
• References:– E.L. Christiansen and D.M. Lear: “Toughened thermal blanket for
micrometeoroid and orbital debris protection”, 2015 Hypervelocity Impact Symposium.
National Aeronautics and Space Administration
13
Protection concept
• Obtain significant improvements in MMOD protection by adding a full-MMOD shield within thermal blanket; i.e., disrupter (bumper), spacer (standoff) and stopper (rear wall)
• 36 hypervelocity impact tests performed on 21 different thermal blanket configurations– Test velocities: 6.89 km/s – 7.16 km/s, and 9.63 km/s– Impact angle: 0 deg (normal to target)– Projectiles: 0.4mm – 6.0mm diameter Al 2017-T4 spheres
• Example result on 0.212 g/cm2 blanket with fiberglass cloth disrupter, 1” thick foam, Spectra-952 stopper– HTIF-11270: No failure from 1.4mm diameter Al projectile @ 7.16 km/s
Front
Spectra
MLI back layer
National Aeronautics and Space Administration
15
Test results: Scale-Up
• 2x scale-up: 0.359 g/cm2 blanket with fiberglass cloth disrupter, 2” thick foam, Spectra-952 stopper– HTIF-11360: No failure from 2.6mm diameter
Al projectile @ 7.10 km/s
• 6x scale-up (0.805 g/cm2) blanket stops a 6.0mm diameter Al projectile at 6.91 km/s
Materials Key
Beta cloth
Fiberglass cloth
Scrim
Aluminized Mylar
Open-cell foam
Spectra-952
Back cover
Front
SpectraMLI back
layer
National Aeronautics and Space Administration
16
Test Results: Design Equations
• Best disrupter materials: beta-cloth and fiberglass fabric
• Light-weight open cell foam used as spacer effective at increasing performance
• Best stopper materials: Spectra 1000-952 and Kevlar KM2-705
• Equations developed to predict performance of several versions of the toughened blanket
Lightening holes added to
foam
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0 2 4 6 8 10 12 14
Criti
cal A
l Dia
met
er (c
m)
Impact velocity (km/s)
Ballistic Limits for toughened thermal blanket, config. 3expect perforation of the blanket at/above curves
• Integrate thin-film piezoelectric sensor into thermal blanket to detect and locate MMOD impact damage– Sensor panels are low mass (0.13 kg/m2), highly
flexible, divided into 48-96 pixels, internal connections made by printed circuitry
Several strike detector panels linked into system at lab
The linked strike detector panels display “hit” information on a spacecraft schematic (hundreds of pixels resolve impact location & damage extent)
Materials KeyBeta clothDisrupterStopperSensor film
Piezoelectric impact sensor film (18" x 16", with 48
pixels)
National Aeronautics and Space Administration
18
Thermal testing
• Thermal-vacuum tests were conducted on several versions of the toughened thermal blanket to determine effective emittance of each blanket– Only slight increase in effective emittance measured (relative to
baseline) and considered acceptable – Data confirmed thermal math models – Mechanical impact tests performed on piezoelectric film indicated no
significant degradation of signal output down to -175F
View of MMOD toughened thermal blankets in thermal vacuum test chamber
Mechanical impact tester (“whacker”) built and operated to -175F to verify capability of impact
detection film at reduced temperatures
National Aeronautics and Space Administration
19
Foam sandwich MMOD shielding
• Honeycomb core sandwich structures are used extensively on spacecraft
• Honeycomb core tends to “channel” debris cloud and results in a relatively poor MMOD shield
• Replacing the honeycomb core with a metallic or ceramic foam provides improved MMOD protection